Added limit on size of AST after expansion of aliases [#CLICKHOUSE-18]

dbms/src/Interpreters/ExpressionAnalyzer.cpp

@@ -83,6 +83,7 @@ namespace ErrorCodes
     extern const int ILLEGAL_AGGREGATION;
     extern const int SUPPORT_IS_DISABLED;
     extern const int TOO_DEEP_AST;
+    extern const int TOO_BIG_AST;
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
@@ -932,6 +933,16 @@ void ExpressionAnalyzer::normalizeTree()
     SetOfASTs tmp_set;
     MapOfASTs tmp_map;
     normalizeTreeImpl(ast, tmp_map, tmp_set, "", 0);
+
+    try
+    {
+        ast->checkSize(settings.limits.max_expanded_ast_elements);
+    }
+    catch (Exception & e)
+    {
+        e.addMessage("(after expansion of aliases)");
+        throw;
+    }
 }
 
 
@@ -942,7 +953,8 @@ void ExpressionAnalyzer::normalizeTreeImpl(
     ASTPtr & ast, MapOfASTs & finished_asts, SetOfASTs & current_asts, std::string current_alias, size_t level)
 {
     if (level > settings.limits.max_ast_depth)
-        throw Exception("Normalized AST is too deep. Maximum: " + settings.limits.max_ast_depth.toString(), ErrorCodes::TOO_DEEP_AST);
+        throw Exception("Normalized AST is too deep. Maximum: "
+            + settings.limits.max_ast_depth.toString(), ErrorCodes::TOO_DEEP_AST);
 
     if (finished_asts.count(ast))
     {

dbms/src/Interpreters/Limits.h

@@ -63,6 +63,7 @@ struct Limits
     M(SettingUInt64, max_pipeline_depth, 1000, "") \
     M(SettingUInt64, max_ast_depth, 1000, "")        /** Checked not during parsing, */ \
     M(SettingUInt64, max_ast_elements, 50000, "")    /**  but after parsing the request. */ \
+    M(SettingUInt64, max_expanded_ast_elements, 500000, "Limit after expansion of aliases.") \
     \
     /** 0 - everything is allowed. 1 - only read requests. 2 - only read requests, as well as changing settings, except for the readonly setting. */ \
     M(SettingUInt64, readonly, 0, "") \

dbms/src/Storages/StorageView.cpp

@@ -38,7 +38,7 @@ BlockInputStreams StorageView::read(
     const unsigned /*num_streams*/)
 {
     processed_stage = QueryProcessingStage::FetchColumns;
-    BlockInputStreams res = InterpreterSelectWithUnionQuery(inner_query->clone(), context, column_names).executeWithMultipleStreams();
+    BlockInputStreams res = InterpreterSelectWithUnionQuery(inner_query, context, column_names).executeWithMultipleStreams();
 
     /// It's expected that the columns read from storage are not constant.
     /// Because method 'getSampleBlockForColumns' is used to obtain a structure of result in InterpreterSelectQuery.

dbms/tests/queries/0_stateless/00596_limit_on_expanded_ast.reference

@@ -0,0 +1 @@
+1

dbms/tests/queries/0_stateless/00596_limit_on_expanded_ast.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+. $CURDIR/../shell_config.sh
+
+exception_pattern="too big"
+
+${CLICKHOUSE_CLIENT} --max_expanded_ast_elements=500000 --query="
+    select 1 as a, a+a as b, b+b as c, c+c as d, d+d as e, e+e as f, f+f as g, g+g as h, h+h as i, i+i as j, j+j as k, k+k as l, l+l as m, m+m as n, n+n as o, o+o as p, p+p as q, q+q as r, r+r as s, s+s as t, t+t as u, u+u as v, v+v as w, w+w as x, x+x as y, y+y as z
+" 2>&1 | grep -c "$exception_pattern"